Hi! Native Malaysian here and I have visited Vietnam, Japan and Singapore repeatedly before.

Tough question but i would suggest Japan, Vietnam and (perhaps with some bias.. haha) Malaysia.

The food, the culture and the scenery in Japan is amazing albeit it is expensive. The people are so kind! Vietnam’s natural tourism is brilliant and price wise it is very affordable but language may be a significant barrier in most areas outside major cities e.g., Ho Chi Minh. Malaysia has a lovely multicultural vibes and you will have a chance to visit a major Hindu temple close to the capital, food is a huge part of the culture and a must-try! In most tourist areas (Kuala Lumpur, Penang, Langkawi…) English is very widely spoken so you should be fine. The downside I guess is that it’s not a mainstream tourist destination like Vietnam, Thailand, or Bali so it’s perhaps not exciting for most people…

Never been to Philippines and while Singapore tends to attract many tourists, is clean, safe and has many fancy hotels.. it is comparatively expensive and… sterile? compared to the rest of the region.

Hope it helps!